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Crypto Tls CVE-2026-32283

| EUVDEUVD-2026-20014 HIGH
Allocation of Resources Without Limits or Throttling (CWE-770)
2026-04-08 Go GHSA-jrg3-gfjw-hm96
Denial Of Service Crypto Tls Go Standard Library
7.5
CVSS 3.1 · NVD
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Establish TLS 1.3 connection
  2. Delivery
    Complete handshake
  3. Exploit
    Send malformed record with multiple KeyUpdate messages
  4. Execution
    Trigger deadlock in crypto/tls state machine
  5. Persist
    Exhaust server resources
  6. Impact
    Denial of service

Vulnerability Assessment

Weakness
CWE
CWE-770
OWASP Top 10:2025
A06:2025 - Insecure Design
ASVS 5.0
V2 - Validation and Business Logic Resource allocation limits
MITRE ATT&CK

1 technique across 1 tactic: Impact

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

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Exploitation Conditions

TLS 1.3 protocol must be enabled and negotiated for the connection (TLS 1.2 and earlier versions are not vulnerable). The attack requires completing the initial TLS handshake to reach the post-handshake phase where KeyUpdate messages are valid. No special server configuration, authentication, or privileged access is required beyond network connectivity to a TLS 1.3-enabled Go service listening on an accessible port. The vulnerability affects both client and server roles in the crypto/tls library, meaning a malicious server could exploit vulnerable Go clients as well as the more common scenario of attackers targeting vulnerable servers.
Impact

Real-world risk is significantly lower than the CVSS 7.5 score suggests. The CVSS vector (AV:N/AC:L/PR:N/UI:N) indicates remote unauthenticated exploitation with low complexity, which technically allows any network attacker to target exposed TLS 1.3 services. However, EPSS exploitation probability of 0.01% (0th percentile) indicates security researchers and threat actors have shown essentially zero interest in weaponizing this flaw. No public exploit code exists and CISA has not added this to the KEV catalog, confirming no observed active exploitation. The impact is purely availability (A:H) with no confidentiality or integrity compromise, limiting attacker incentive. Applying the SSVC framework: exploitation status is none, technical impact is partial (DoS only, no data exposure), and while the attack is automatable against internet-facing TLS 1.3 endpoints, the business impact depends heavily on service criticality. This vulnerability merits routine patching priority rather than emergency response, particularly since patches are readily available and easily applied via Go version upgrades. Organizations not exposing TLS 1.3 services to untrusted networks face negligible risk.
Exploit ScenarioDerived

An attacker establishes a TLS 1.3 connection to a vulnerable Go service (web server, API endpoint, database listener). After the initial handshake completes, the attacker crafts a malicious TLS record containing multiple KeyUpdate messages instead of the standard single-message-per-record format. When the Go crypto/tls library processes this record, it enters a deadlock state attempting to handle the unexpected message sequence, causing the connection goroutine to hang indefinitely. By repeating this attack across multiple connections, the attacker exhausts server resources (goroutines, memory, file descriptors), ultimately rendering the service unresponsive to legitimate clients and achieving denial of service without requiring authentication or special privileges.
This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
Patch available 0.0% exploitation probability (EPSS)

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AnalysisAIv1 – Apr 15, 2026

Deadlock in Go's crypto/tls library (versions <1.25.9 and 1.26.0-1.26.1) allows remote unauthenticated attackers to trigger denial of service via multiple TLS 1.3 post-handshake key update messages sent in a single record. CVSS 7.5 (High) with network attack vector and low complexity, but EPSS score of 0.01% (0th percentile) indicates minimal real-world exploitation probability. Vendor-released patches available in Go 1.25.9 and 1.26.2, with no public exploit code identified at time of analysis.

RemediationAI

Upgrade to Go version 1.25.9 or 1.26.2 or later, which contain the fix implemented in code review https://go.dev/cl/763767. Recompile all affected applications with the patched Go toolchain to ensure the crypto/tls library remediation is incorporated into binary artifacts. The official Go security announcement at https://groups.google.com/g/golang-announce/c/0uYbvbPZRWU provides release notes and migration guidance. If immediate upgrade is not feasible, temporary workaround options include disabling TLS 1.3 protocol support (forcing TLS 1.2 via MaxVersion configuration in tls.Config) or implementing connection timeouts and resource limits to mitigate deadlock impact, though these reduce functionality and security posture. Organizations should prioritize the upgrade path over workarounds given the straightforward remediation and availability of stable patched releases.

Affected VersionsENISA

crypto/tls 0 <1.25.9
crypto/tls 1.26.0-0 <1.26.2

Affected Packages

go stdlib fix: 1.25.9, 1.26.2
euvd crypto_tls fix: 1.25.9, 1.26.2

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 2 packages in go, euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

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Technical ContextAI · show details

This vulnerability affects the Go standard library's crypto/tls implementation, specifically the handling of TLS 1.3 post-handshake key update messages as defined in RFC 8446. In TLS 1.3, KeyUpdate messages allow either peer to request cryptographic key material refresh without full renegotiation. The Go crypto/tls package fails to properly handle scenarios where an attacker sends multiple KeyUpdate messages bundled within a single TLS record (rather than separate records). This triggers a deadlock condition in the connection state machine, causing the TLS session to hang indefinitely and consume resources (CPU cycles, memory buffers, goroutines) without releasing them. The flaw is specific to TLS 1.3's post-handshake messaging mechanism and does not affect TLS 1.2 or earlier protocols, which lack this key update feature. The affected CPE (cpe:2.3:a:go_standard_library:crypto/tls) indicates any Go application using the standard library's TLS implementation for server or client operations with TLS 1.3 enabled is potentially vulnerable.

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Severity by source

NVD PRIMARY 7.5 HIGH
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
SUSE HIGH
Red Hat 7.5 HIGH

Primary rating from NVD.

CVSS VectorNVD

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

Lifecycle Timeline

3
CVSS changed
Apr 13, 2026 - 19:37 NVD
7.5 (HIGH)
Patch released
Apr 08, 2026 - 02:30 nvd
Patch available
CVE Published
Apr 08, 2026 - 01:06 nvd
N/A

DescriptionNVD

If one side of the TLS connection sends multiple key update messages post-handshake in a single record, the connection can deadlock, causing uncontrolled consumption of resources. This can lead to a denial of service. This only affects TLS 1.3.

Executive ViewAI

Why It Matters

Go's crypto/tls library (versions before 1.25.9 and 1.26.0-1.26.1) contains a deadlock vulnerability allowing unauthenticated remote attackers to trigger denial of service through crafted TLS 1.3 messages, potentially disrupting services that depend on Go's standard TLS implementation. Organizations running affected Go versions in production should prioritize patching to restore service availability and resilience against network-based attacks.

Business Impact: High
Compensating Controls

Apply vendor patch. Interim mitigations pending patch deployment: disable TLS 1.3 support at the application or load balancer level if operationally feasible, or implement rate-limiting on TLS handshake attempts to reduce attack surface; however, patching is the definitive remediation.

Threat Intelligence Overview

EPSS Score
0.0%
Top 100% exploitable
Data Quality
7 sources
Confidence: High
EUVD NVD CVE.org EPSS Vulnrichment Vendor VulDB

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity HIGH
CISA KEV No
Public POC No
EPSS 0.0%
Patch available Yes
Active threat No
Deciding rule
HIGH severity (CVSS 7.0-8.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision
Scheduled
Exploitation
None
System Exposure· derived
Open
Automatable
Yes
Human Impact
High
Technical Impact
Partial

Priority Score

38
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +38
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Denial of Service MEDIUM

Denial of Service attacks render applications or systems unavailable by overwhelming resources or triggering failure conditions.

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CVE-2017-5850 HIGH POC
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Same technique Denial Of Service

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CVE-2015-5119 CRITICAL POC
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CVE-2011-2462 CRITICAL POC
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CVE-2011-0611 HIGH POC
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CVE-2012-1889 HIGH POC
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CVE-2012-0507 CRITICAL POC
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CVE-2014-1761 HIGH POC
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CVE-2015-5122 CRITICAL POC
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CVE-2011-0609 HIGH POC
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Vendor StatusVendor

SUSE

Severity: High
Product Status
SUSE Linux Enterprise Desktop 15 SP7 SUSE Linux Enterprise High Performance Computing 15 SP7 SUSE Linux Enterprise Module for Development Tools 15 SP7 SUSE Linux Enterprise Server 15 SP7 SUSE Linux Enterprise Server for SAP Applications 15 SP7 Fixed
SUSE Linux Enterprise High Performance Computing 15 SP4-ESPOS Fixed
SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS Fixed
SUSE Linux Enterprise High Performance Computing 15 SP5-ESPOS Fixed
SUSE Linux Enterprise High Performance Computing 15 SP5-LTSS Fixed

References

Advisories & patches
ADVISORY https://access.redhat.com/errata/RHSA-2026:10217 ADVISORY https://access.redhat.com/errata/RHSA-2026:10219 ADVISORY https://access.redhat.com/errata/RHSA-2026:10704 ADVISORY https://access.redhat.com/errata/RHSA-2026:11507 ADVISORY https://access.redhat.com/errata/RHSA-2026:11514 ADVISORY https://access.redhat.com/errata/RHSA-2026:11704 ADVISORY https://access.redhat.com/errata/RHSA-2026:11711 ADVISORY https://access.redhat.com/errata/RHSA-2026:11712 ADVISORY https://access.redhat.com/errata/RHSA-2026:11863 ADVISORY https://access.redhat.com/errata/RHSA-2026:11881 ADVISORY https://access.redhat.com/errata/RHSA-2026:14162 ADVISORY https://access.redhat.com/errata/RHSA-2026:14200 ADVISORY https://access.redhat.com/errata/RHSA-2026:14391 ADVISORY https://access.redhat.com/errata/RHSA-2026:15980 ADVISORY https://access.redhat.com/errata/RHSA-2026:16021 ADVISORY https://access.redhat.com/errata/RHSA-2026:16024 ADVISORY https://access.redhat.com/errata/RHSA-2026:16101 ADVISORY https://access.redhat.com/errata/RHSA-2026:16102 ADVISORY https://nvd.nist.gov/vuln/detail/CVE-2026-32283 ADVISORY https://vuldb.com/vuln/355985 ADVISORY https://www.suse.com/support/update/SUSE-SU-2026:1320/ ADVISORY https://www.suse.com/support/update/SUSE-SU-2026:1321/ REF https://access.redhat.com/errata/RHSA-2026:16875 REF https://access.redhat.com/errata/RHSA-2026:17075 REF https://access.redhat.com/errata/RHSA-2026:17084 REF https://access.redhat.com/errata/RHSA-2026:17287 REF https://access.redhat.com/errata/RHSA-2026:18027 REF https://access.redhat.com/errata/RHSA-2026:18032 REF https://access.redhat.com/errata/RHSA-2026:19126 REF https://access.redhat.com/errata/RHSA-2026:19132 REF https://access.redhat.com/errata/RHSA-2026:19133 REF https://access.redhat.com/errata/RHSA-2026:19134 REF https://access.redhat.com/errata/RHSA-2026:19135 REF https://access.redhat.com/errata/RHSA-2026:19136 REF https://access.redhat.com/errata/RHSA-2026:19137 REF https://access.redhat.com/errata/RHSA-2026:19139 REF https://access.redhat.com/errata/RHSA-2026:19144 REF https://access.redhat.com/errata/RHSA-2026:19156 REF https://access.redhat.com/errata/RHSA-2026:19350 REF https://access.redhat.com/errata/RHSA-2026:19351 REF https://access.redhat.com/errata/RHSA-2026:19352 REF https://access.redhat.com/errata/RHSA-2026:19353 REF https://access.redhat.com/errata/RHSA-2026:19369 REF https://access.redhat.com/errata/RHSA-2026:19450 REF https://access.redhat.com/errata/RHSA-2026:19550 REF https://access.redhat.com/errata/RHSA-2026:19634 REF https://access.redhat.com/errata/RHSA-2026:19714 REF https://access.redhat.com/errata/RHSA-2026:19715 REF https://access.redhat.com/errata/RHSA-2026:19719 REF https://access.redhat.com/errata/RHSA-2026:19720 REF https://access.redhat.com/errata/RHSA-2026:19721 REF https://access.redhat.com/errata/RHSA-2026:19722 REF https://access.redhat.com/errata/RHSA-2026:19750 REF https://access.redhat.com/errata/RHSA-2026:19839 REF https://access.redhat.com/errata/RHSA-2026:20556 REF https://access.redhat.com/errata/RHSA-2026:20569 REF https://access.redhat.com/errata/RHSA-2026:20570 REF https://access.redhat.com/errata/RHSA-2026:20571 REF https://access.redhat.com/errata/RHSA-2026:20607 REF https://access.redhat.com/errata/RHSA-2026:20608 REF https://access.redhat.com/errata/RHSA-2026:20609 REF https://access.redhat.com/errata/RHSA-2026:21769 REF https://access.redhat.com/errata/RHSA-2026:22347 REF https://access.redhat.com/errata/RHSA-2026:22423 REF https://access.redhat.com/errata/RHSA-2026:22450 REF https://access.redhat.com/errata/RHSA-2026:22485 REF https://access.redhat.com/errata/RHSA-2026:22709 REF https://access.redhat.com/errata/RHSA-2026:22713 REF https://access.redhat.com/errata/RHSA-2026:22714 REF https://access.redhat.com/errata/RHSA-2026:22937 REF https://access.redhat.com/errata/RHSA-2026:23102 REF https://access.redhat.com/errata/RHSA-2026:23103 REF https://access.redhat.com/errata/RHSA-2026:23228 REF https://access.redhat.com/errata/RHSA-2026:23345 REF https://access.redhat.com/errata/RHSA-2026:24337 REF https://access.redhat.com/errata/RHSA-2026:24470 REF https://access.redhat.com/errata/RHSA-2026:24761 REF https://access.redhat.com/errata/RHSA-2026:24762 REF https://access.redhat.com/errata/RHSA-2026:25248 REF https://access.redhat.com/errata/RHSA-2026:25250 REF https://access.redhat.com/errata/RHSA-2026:25251 REF https://access.redhat.com/errata/RHSA-2026:25252 REF https://access.redhat.com/errata/RHSA-2026:26447 REF https://access.redhat.com/errata/RHSA-2026:26571 REF https://access.redhat.com/errata/RHSA-2026:26636 REF https://access.redhat.com/errata/RHSA-2026:27076 REF https://access.redhat.com/errata/RHSA-2026:28038 REF https://access.redhat.com/errata/RHSA-2026:28047 REF https://access.redhat.com/errata/RHSA-2026:28074 REF https://access.redhat.com/errata/RHSA-2026:29035 REF https://access.redhat.com/errata/RHSA-2026:29195 REF https://access.redhat.com/errata/RHSA-2026:29455 REF https://access.redhat.com/errata/RHSA-2026:29703 REF https://access.redhat.com/errata/RHSA-2026:33722 REF https://access.redhat.com/errata/RHSA-2026:34192 REF https://access.redhat.com/errata/RHSA-2026:34196 REF https://access.redhat.com/errata/RHSA-2026:34197 REF https://access.redhat.com/errata/RHSA-2026:34365 REF https://access.redhat.com/errata/RHSA-2026:36796 REF https://access.redhat.com/errata/RHSA-2026:39810 REF https://access.redhat.com/errata/RHSA-2026:41019 REF https://access.redhat.com/errata/RHSA-2026:41928 REF https://access.redhat.com/errata/RHSA-2026:42644 REF https://access.redhat.com/errata/RHSA-2026:47712 REF https://access.redhat.com/errata/RHSA-2026:47714 REF https://access.redhat.com/errata/RHSA-2026:47716 REF https://access.redhat.com/errata/RHSA-2026:47719 REF https://access.redhat.com/errata/RHSA-2026:47721 REF https://access.redhat.com/errata/RHSA-2026:47722 REF https://access.redhat.com/errata/RHSA-2026:47910 REF https://access.redhat.com/errata/RHSA-2026:48036 REF https://access.redhat.com/errata/RHSA-2026:48790 REF https://access.redhat.com/errata/RHSA-2026:49509 REF https://access.redhat.com/errata/RHSA-2026:49600 REF https://access.redhat.com/errata/RHSA-2026:49944 REF https://access.redhat.com/errata/RHSA-2026:51288 REF https://access.redhat.com/errata/RHSA-2026:54191 REF https://access.redhat.com/errata/RHSA-2026:54435 REF https://access.redhat.com/errata/RHSA-2026:54757 REF https://access.redhat.com/errata/RHSA-2026:55898 REF https://access.redhat.com/errata/RHSA-2026:55900 REF https://access.redhat.com/errata/RHSA-2026:55901 REF https://access.redhat.com/errata/RHSA-2026:55902 REF https://access.redhat.com/errata/RHSA-2026:55903 REF https://access.redhat.com/errata/RHSA-2026:56910 REF https://access.redhat.com/errata/RHSA-2026:57409 REF https://access.redhat.com/errata/RHSA-2026:57801 REF https://access.redhat.com/errata/RHSA-2026:57802 REF https://access.redhat.com/errata/RHSA-2026:60520 REF https://access.redhat.com/errata/RHSA-2026:65126 REF https://access.redhat.com/errata/RHSA-2026:65343 REF https://access.redhat.com/errata/RHSA-2026:65514 REF https://access.redhat.com/errata/RHSA-2026:66022 REF https://access.redhat.com/errata/RHSA-2026:66084 REF https://access.redhat.com/errata/RHSA-2026:66401 REF https://access.redhat.com/errata/RHSA-2026:66523 REF https://access.redhat.com/errata/RHSA-2026:67319 REF https://access.redhat.com/errata/RHSA-2026:68504 REF https://access.redhat.com/errata/RHSA-2026:7291 REF https://access.redhat.com/errata/RHSA-2026:7385 REF https://access.redhat.com/security/cve/CVE-2026-32283 REF https://bugzilla.redhat.com/show_bug.cgi?id=2456338 REF https://go.dev/cl/763767 REF https://go.dev/issue/78334 REF https://groups.google.com/g/golang-announce/c/0uYbvbPZRWU REF https://pkg.go.dev/vuln/GO-2026-4870 REF https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-32283.json

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